Of the many types of child-resistant closures for containers in which dangerous and harmful substances are packaged, those which have been most successful seem to have two basic concepts underlining their design. First, from the standpoint of the original manufacturer and utilization by people who initially fill the containers, the caps or closures for the containers should be so designed as to enable their emplacement on the containers by the use of standard capping machines. Second, although a number of two-piece child-resistant caps have been designed and commercialized, if the cap can be made in merely one unitary piece the cost of manufacturing molds is reduced and assembly of the two parts is eliminated.
From the standpoint of effective child-resistance, regardless of whether the cap is one piece or two piece, it has been found that requiring two motions of different types usually provides the most effective resistance to opening by small children. Preferably, however, one of the two motions should not merely be either pulling or pushing on the cap because the small child often does one or the other of these actions when he attempts to remove the cap.
The closure shown in Julian U.S. Pat. No. 3,993,209 is an inverted cup-shaped cap having threads on its single skirt which mate with threads on the container neck and having a locking ring depending from the cap skirt which is connected to the cap skirt by integral flexible webs. The locking ring is resilient and carrys at least one locking lug which cooperates with a stop on the container so when the cap is screwed down onto the container tightly the lug on the cap ring passes the container stop and the cap cannot be removed from the container without squeezing the depending ring to flex that portion of the ring carrying the lug outwardly in order that it can pass the container stop when the cap is unscrewed. This combination of squeezing at a particular place and rotating renders the cap quite child-resistant.
It is the principal object of the instant invention to provide child-resistant locking means for a container and cap which requires both a squeezing and rotating action in order to remove the cap from the container.
It is yet another object of the instant invention to provide child-resistant means for a closure so designed that when it is attempted to remove the cap from the container by merely rotating the cap, the child-resistant means are rendered yet more effective.
And a still further object of the instant invention is to provide a unitary child-resistant cap for use on a closed container having a cooperating neck finish in which the cap can be no longer axially than a standard cap not provided with child-resistant means and which cap also can be utilized to close a container not provided with a cooperating neck finish when the child-resistant feature is not required.
And a still further object of the instant invention is to provide child-resistant means for a cap and container so designed as to require a minimum of material for fabrication of the cap thus to minimize the cost.